The difficulty is much higher than Delve 1.0 in pre-adoulin gear (we were one of the first groups to clear tojils back then, the first to 5NM shark and bee across all servers)
Back then, you can still hit with just SV Madrigals, as Bolsters were saved for stuns only because there were no ilevel magic accuracy staff, stuns will get resisted after a minute with apajamasII.
At 143, with SV Madsx2, hunters, Precision Torpor (non bolstered) and distract, and oceanfin etc... hit rate is about 30% lol
In order to win 143 boss, we used 4 (Punyanya, Rokumo, Nivlakian and Katsuoch) Idris GEO's full time bolstering in turns (one more Non-Idris had to bolster focus/languor as the guard NM was Insidious), full time SV Mads etc... In total, 5 freaking Geo's! lol
Bear in mind, this is not with Occult guard NM (evasion boost). If i recall correctly, the guards were Insidius and Brawny (took us 5 times to get to boss with multiple sacs just to get this guard NM Combo, we warp out if it's Occult OR Steadfast as it will be truly impossible to win)
On our winning run, we almost lost at 5% as our last bolster wore, but one of the two wildcard was a success and we managed to wither it down with a final SV and Bolster.
So you could see our frustration here, 18 of us grinding many hours just to get the correct guard NM to pop, and finally won..... just to have our KI's taken away for nothing?
http://chihiromom.blog.fc2.com/blog-entry-35.html
Ramzi, click on the above link, it's from one of my team members giving full details/strats involved on clearing 142 and beyond. It's pretty detailed lol
http://chihiromom.blog.fc2.com/blog-entry-32.html
This was minute by minute guide when we cleared 141
And finally,
http://chihiromom.blog.fc2.com/blog-entry-39.html
The dreaded Lost KI post